Levelling valve assembly

ABSTRACT

The levelling valve assembly controls the supply and discharge of air to and from a pneumatic spring by providing a valve operating lever supporting shaft separate from the drive shaft for converting the sensed variations of chassis height into a corresponding rotational movement with a damper device resiliently connected therebetween.

I Unlted States Patent [151 3,659,870 Okuyama 1 May 2, 1972 [54]LEVELLING VALVE ASSEMBLY [56] References Cited [72] Inventor: TeijiOkuyama, Kariya, Japan UNITED STATES PATENTS [73] Assignee: Aisin SeikiKabushiki Kaiha, Kariya,.lapan 3,508,585 4/1970 Kurichh ..280/124 F I3,599,675 8/1971 Slevenpiper... ....l37/636.l [221 3,490,495 1/1970Green..... ....l37/636.l [21] Appl. No.: 75,517 3,140,725 7/1964 Alfieri..137/636.l X

Primary ExaminerPhilip Goodman [30] Foreign Application Priority DataAttorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Sept. 26,1969 Japan ..44/77252 The levelling valve assembly controls the supplyand discharge 52 vs. C]. ..280/124 F, 280/6 H 137/595 air and aPneumatic swing by Pmviding a valve 137/636 operating lever supportingshaft separate from the drive shaft 511 1111.01 ..B60g 17/00 forconverting the sensed variations of chassis height into a [58] FieldofSearch ..280/124 F,6,6H; 137/595, corresponding rotationa mo ementwith a damper de 137/6361 resiliently connected therebetween.

5 Claims, 8 Drawing Figures LEVELLING VALVE ASSEMBLY PNEUMATIC SPRINGPatented May 2, 1972 3,659,870

2 Sheets-Sheet l n Hit, LEVELLING VALVE ASSEMBLY Patented May 2, 1972 2Sheets-Sheet 2 :Sll h I LEVELLING VALVE ASSEMBLY This invention relatesto improvements in and relating to a valve assembly which is arranged ina pneumatic system for a pneumatic vehicle suspension means and adaptedfor automatic adjustment of the chassis height from the axle of thevehicle, responsive to variation in the chassis deviated variation inthe chassis height caused by increase or decrease of static load mountedon the chassis from a standardized and preset value of that height.

As commonly known among those skilled in the art, conventional leafsprings and coil springs, or briefly mechanical springs are beingrapidly replaced by pneumatic springs, when seen at least in the fieldof automotive, railroad and the like powered vehicles, thanks to thesuperior performance of the pneumatic springs capable of providing amore pleasant travelling feelings to the passengers and a highlystabilized mounting capability of vehicle chassis and live loadsthereon.

Since the pneumatic spring has conventionally a kind of bellows ordiaphragm structure, it is possible to adjust the pneumatic pressurecontained in the spring, and indeed, in response to occasional variationin the static loads on the chassis and for keeping the chassis height ata predetermined standard optimum value.

The levelling valve assembly to which the subject matter of theapplication belongs has been deviced hithertofore in a various andnumerous ways. In general, however, this kind of levelling valveassembly comprises a control valve means having such a structure ascontrolling the supply and discharge of the high pressure air to andfrom the pneumatic spring, respectively. In addition, it comprises adamper means operatively connected with the valve control or operatingmeans for retarding the valving action or the automatic chassis heightadjusting movement so as to avoid too much sensitive or overtravelcontrol, responsive to the cornering or to road surface uneveness, orthe like minor influencing chassis height as frequently met duringtravel of the powered vehicle. The levelling valve assembly may furthercontain a further overtravel prevention means having a damper pistonwhich absorbs a part of the chassis movement caused by static loadvariation and is adapted for transfer the sensed chassis heightvariation to the valve control mechanism.

It is a grave drawback frequently encountered with use of theconventional levelling valves that there is a substantial fluctuation inthe return movement period of the chassis height variation-sensing andresponsive motion transmittingmeans embodied in that kind of valves.

It is the main object of the invention to provide an efficient levellingvalve assembly capable of obviating substantially the aforementionedconventional drawback.

For this purpose and according to this invention, the levelling valveassembly is so designed and arranged that the valve operating leversupporting shaft and the drive shaft for converting the sensed variationof the chassis height into a corresponding rotational movement areseparately provided and arranged, a damper means being inserted betweensaid supporting shaft and said drive shaft. Said damper means comprisesa damper piston which is connected through a resilient means with saiddrive shaft; and said supporting shaft and said resilient means througha connecting member. By adapting these measures, it is possible toprovide a highly efficient levelling valve assembly capable minimumfrictional resistance and providing an accurate operation lag in themovement of the air supply and discharge valves and having a highlyimproved sealed condition.

These and further objects, features and advantages of the invention willappear more apparent when read the following detailed description byreference to the accompanying drawings illustrative of a preferredembodiment of the levelling valve assembly embodying the principles ofthe invention and shown only by way of example. In the drawings:

FIG. 1 is a plan view of the sole embodiment of the invention.

FIG. 2 is an axially sectional view of the embodiment shown in FIG. 1.

FIG. 3 is a side view of the main part of the levelling valve assemblywhen viewed from the side of a showing line IIIlll in FIG. 2, and uponremoval of a certain part from the assembly for clear demonstration ofthe inner working parts thereof.

FIG. 4 is a sectional view taken substantially along a section line IVIV shown in FIG. 2.

FIG. 5 is a sectional view taken substantially along a section line V Vshown in FIG. 1.

FIG. 6 is a sectional view taken substantially along a section line VIVI shown in FIG. 2, wherein, however, the assembly is in its off-serviceposition.

FIG. 7 is a similar view to FIG. 6, illustrative of the same assembly inits working position.

FIG. 8 is a schematic representation ofa pneumatic suspension system towhich the levelling valve assembly according to the invention is fitted.

Referring now to the accompanying drawings, the invention will bedescribed in detail and by way of example.

In the drawings, numeral 10 denotes a main body of the levelling valveassembly according to this invention, said body being fixedly attachedto the chassis of a powered vehicle, preferably an automotive vehicle,although not shown. In addition, the assembly is mechanically connectedwith the axle housing of the vehicle, not shown, through an elongatedarm 11.

It will thus be seen that when the chassis height which means the mutualdistance between the chassis and the axle housing is subjectedmodification, the arm 11 is turned to a larger or lesser degree, as willbe more fully described hereinafter and a pneumatic communicationcontrol valve is thereby actuated.

The main body 10 is pneumatically connected through a piping 15, a highpressure air reservoir 12, a piping 100, a air compresser 18, a piping19, a lower pressure air reservoir 13 and a further piping 16 in acirculating manner.

The main body 10 comprises two separate castings 10a and 10b detachablyunited together along a separating plane III- III by means ofa pluralityof fixing screws of which only one is shown representatively at 102 inFIG. 1. In HO. 3, however, a plurality of tapped holes 103 serving forthis purpose are seen at 103.

The main body 10 is formed with a vertical bore 20, when seen in FIGS.2, 6 and 7, for mounting an overtravel mechanism to be described, andwith a lateral inside space 21 for receiving an operating lever for apneumatic communication control valve which will be more fully describedhereinafter.

At an upper part of the vertical bore 20, a lateral or drive shaft 22 isrotatably mounted by means of a pair of bearing rings 23 and 24 whichare fixedly positioned at the both sides of the bore 20 in FIG. 2. Thelateral shaft 22 protrudes from the main body 10, said arm 11 beingfixedly attached to the protruding end of the lateral shaft 22 by meansof a fixing bolt 25. Around the shaft 22, a sealing ring 26 made of aresilient material such as rubber is sealingly provided in closeproximity of the bearing ring 24 and in the outer wall part of the bodyelement 10a.

The shaft 22 is formed at an intermediate point thereof in proximity ofits inner end and in registration with the central axis of the verticalbore 20 with a substantially reduced part 27 to which a spring mount 28is fixedly attached by means of a bolt 30 and a nut 31, the upper end ofa closedly wound coil spring 29 abutting under pressure against thespring mount 28 and the lower end of said spring abutting on themounting disc 132 rigidly formed on the upper end ofa rod member 33,This rod member 33 extends vertically into the inside space of a lateralbore 36 formed through a damping piston 35 reciprocatably received in across bore 34 which is formed in the lower main body element 10b, whenseen in FIG. 2. The lower end of the rod member 33 is enlarged, so as toform a semi-ball end 32. The cross bore 34 is kept in fluidcommunication with the lower end of the vertical bore 20 through anintermediate passage 43 formed into a neck.

The damping piston 35 is formed with a pair of longitudinal passages 37and 38 as shown in FIGS. 4, 6 and 7, said passages being normally closedresiliently by respective flap valves 39 and 40 which are fixedlymounted at their respective root portions on the related end surfaces ofthe piston by respective fixing screws 41 and 42. The axial length ofthe piston 35 is so selected as being slightly longer than the diameterof the intermediate or necked passage 43. As seen from FIGS. 2, 4, 6 and7, there is provided an appreciable diametral gap plays between thepiston 35 and the inside wall surface of cross bore 34 for allowing aresistive passage of a high viscosity damping liquid contained in thebore 34, as will be more fully described hereinafter.

The upper end of the vertical bore 20 is tightly closed by a closurecover 44 made preferably of a synthetic resin for preventing escapementof splashed liquid particles from within the interior of the verticalbore 20 when the valve assembly is in its operating condition.

A further lateral bore 104 is bored in the upper body element a as seenin FIG. 2 in a crossing manner with the vertical bore and kept incommunication with the inside space 21 and a pin or support shaft 45 isreceived in the bore 104, the inner end of said pin projecting into thevertical bore 20. The pin 45 is formed at its intermediate point with areduced and flattened portion 46 and a Y-lever 47 adapted for control ofthe pneumatic communication control means to be described is attachedfixedly to said portion 46 by means of a fixing bolt 48. At the bothsides of said flattened portion 46, the pin 45 is sealed off by means ofresilient O-rings 49 and 50 for preventing any leakage of high pressureair from the space at 21 which space is filled with such air, as will bemore fully described hereinafter.

Theinside space 21 is divided into two compartments 21a and 21b whichare in communication with lateral tapped bores 51 and 52, respectively,and valves 53 and 54 are held firmly in position in these bores 51 and52, respectively. These bores are insulated from pneumatic communicationwith each other.

These valves 53 and 54 are provided with respective on-off control rods55 and 56, respectively. These rods are so designed and arranged, aswill be most clearly seen from FIG. 5, that they are slidinglycontrolled by the Y-lever 47 for performing on-off control of therelated valves. Parts 51 and 52' of the lateral bores 51 and 52constitute respective high pressure air chambers, one of which 51 isconnected through a check valve 57 and piping 15 with the high pressureair reservoir 12.

The provision of this check valve 57 serves for the preven tion ofescapement of pressure air contained in the pneumatic spring 67, shouldthere be a bursting of the piping 15 extending between the high pressurecontrol valve 53 and the reservoir 12.

Check valve 57 comprises a male-threaded hollow body 53a, a spring mount58 held firmly therein, spring 59, a valve disc 60 and a check valveseat member 66, said valve disc 60 closing normally the axial passageopening 15' bored through said member 66 and a filter disc 61 made of asintered porous metal being provided in contact with the outer end ofsaid seat member 66 for removal of entrained dust particles from thesupplied high pressure air stream from the reservoir 12 through thepiping 15.

To the inwardly projecting end 45 and a pin 62 fixedly attached to theenlarged semi-spherical end 32 of rod 33, a connecting rod 63 isconnected with its both ends. More precisely, the upper end of said rod63 is fixedly connected to the pin end 45' by means of a bolt 64. Thelower end of said rod 63 is formed into a fork having arms 63a and 63bembracing the pin 62 with a certain idle gap delta" specifically shownin FIG. 4.

A lock bolt 65 passes threadedly through the arm 11, as most clearlyseen from FIG. 2, serving for adjustable setting of the valves 53 and 54in their neutral position. For this purpose, valve rods 55 and 56 arepreset to have predetermined relative gaps to lever 47 and then, bytrial and error method, the neutral position of the lever is set forproviding equal operational lags to the air supply and discharge valves.When this position has been set, the pointed tip end of lock bolt 65 isfixed in position by punching a small recess into the outside wall ofthe upper body member 10a for engagement with the pointed lock bolt end.

For ready use of the above-mentioned apparatus, it is suffcient to equipthe latter to a powered vehicle upon completion of the presetting of thechassis to a certain standardized height peculiar to a specific model ofthe vehicle, and then to release the lock bolt 65. In this way, thechassis can be maintained substantially always at the standardized andpreset height valve, as will be more fully described hereinbelow.

The operation of the apparatus so far shown and described is as follows:

Now it is assumed that the chassis load is reduced and the chassisheight is increased beyond a predetermined value, the shaft 22 which isconnected through arm 11 with the axle housing will swivel acorresponding angle in the direction shown by a small arrow P in FIG. 2.

By this swivel movement of shaft 22, coil spring 29 is subjectedforcibly to a deformation as shown in FIG. 7, a reaction beingtransmitted from the coil to damper piston 35 so as to urge the latterto shift rightwards. Since the axial passage 37 provided in the damperpiston 35 is closed by flap valve 40, the viscous damping liquid fillingthe right-hand liquid chamber of the cylinder bore 34 is pressed out bythis shifting movement of piston 35 through the small idle gaps formedbetween the bore and the piston into the vertical bore 20 and also intothe damper piston bore 36. During passage of the damping liquid throughthe said small idle gaps, the liquid flow will naturally be subjected toa substantial fluid resistance which will retard the shifting movementof said damper piston.

During this rightward shift movement of the damper piston, the oppositepassage opening 38 in the piston is opened by forcibly receding therelated flap valve by action of the flowing damping liquid. Therefore,the part of the damping liquid confined in the piston bore 36 will flowinto the left-hand liquid chamber of the bore 34, without subjecting toa considerable flow resistance.

With further small rightward shift of damper piston 35 against the saidfluid resistance, the left-hand liquid chamber of cylinder bore 34 willbecome in full communication with the bore 20. Only under such operatingcondition, the connecting rod 63 which has had a predetermined idle gapdelta relative to the pin 62 fixed on the lower end of spring-mountingrod 33 will follow after the shifting movement of damping piston 35.

Since the connection between the pin end 45' and the upper end ofconnecting rod 63 is made firmly, the pin 22 will precisely follow afterthe angular movement of connecting rod 63. At this stage, the Y-lever 47will shift leftward when seen in FIG. 5, but, since there is apredetermined idle gap alpha" between the lever 47 and the operating rod56, the valve operating lever 47 will move beyond the predeterminedvalue alpha, only when the damper piston 35 linked by connected withsaid lever. By this movement, the operating rod 56 is attracted and theair discharge valve 54 is opened. By this valving operation, a part ofthe pressure air contained in the pneumatic spring 67 will escapethrough the pipings 17 and 16 to the low pressure reservoir 13. Thus,the chassis height recovers its standard preset value.

When it is assumed that the chassis load is increased and the chassisheight is reduced beyond the predetermined preset value, the shaft 22will make a reversed turning movement relative to the case of theforegoing.

Therefore, the Y-shaped, valve control lever 47 will shift rightwards inFIG. 5, thereby operating rod 55 of compressed air supply valve 53 beingpressed for opening the valve. A part of the high pressure air containedin the reservoir 12 will be delivered therefrom through piping 15, airfilter 61, check valve 57, valve 53 and a further piping 17 to thepneumatic spring 67, thereby the chassis height being increased to thepreset value.

Upon recovery of the chassis height to the standard preset value in theaforementioned way, air delivery and air discharge operations throughthe valve means must preferably be brought into stoppage.

When the time delay during the return movement of the damper piston fromits shifted to its neutral position, the valve 53 or 54 will be keptopen even after attainment of the standard chassis height, which resultsin an overadjustment.

In the arrangement according to the invention, the flap valves 39 and 40will serve highly effectively for avoiding such overadjustment.

When the damper piston 35 initiates its return movement from itsmaximumly shifted position back to its neutral-one, either of these flapvalves 39 or 40, which may be as the occasion desires it, will beautomatically opened, and thus, a viscous flow of the damping liquidfrom piston bore 36 through the corresponding passage 37 or 38 to theleft-hand or right-hand liquid chamber of the cylinder bore 34 will besubjected to almost no fluid resistance and in an easy way.

Therefore, the damper piston 35 will go back to its neutral positionwithin a possible minimum period. Since, as mentioned above, there is acertain predetermined idle play alpha between the Y-lever 47 andvalve-control rods 55;56 in their off-service stage, there will be soonestablished and maintained between these rods, on the one hand, and thelever 47 on the other upon return movement of the damper piston to itsneutral position. Thus, valves 53 or 54 will be closed almost instantly.An overadjustment of chassis height can be substantially obviated inthis manner.

In the arrangement according to this invention, the closedly woundspring acts practically as an overtravel mechanism which is capable ofresponding quickly and sensitively the variation in the chassis heightand of obviating unavoidable fluctuation ofthe return lag in the abovesence.

Since the overtravel mechanism is subjected to a possible smallestfrictional resistance, the frequently met disadvantageous phenomena suchas cornering, oversensitive response to chassis height variation in caseof braking and accelerating the vehicle can substantially obviated.

The embodiments of the invention in which an exclusive property orprivilege is claimed are as follows:

1. A levelling valve assembly comprising:

a. a main body positioned between a vehicle chassis and a vehicle axleand connected pneumatically with a high pressure air reservoir, a lowpressure reservoir and a pneumatic spring;

b. a drive shaft mounted in part of bore means formed in said main body,a chassis height sensing arm being supported on one end of said shaftand adapted for conversion of chassis height variation into acorresponding angular movement;

c. a supporting shaft for supporting a valve-operating lever, said shaftbeing mounted in said housing with one end thereof extending into saidbore means;

. a control lever fixedly attached to said supporting shaft;

. control valve means comprising a discharge valve and a supply valve,said valves being adapted for being controlled by said control lever;

f. a damping mechanism provided between said drive shaft and saidsupporting shaft;

g. a piston slidably mounted within said damping mechanism;

. a resilient connecting member, one end of the latter being kept inengagement with said drive shaft and the opposite end being kept inengagement with said piston; and

i. a connecting lever one end of which is attached to said supportingshaft and the opposite end of which is adapted for cooperation with saidresilient connecting member.

2. Levelling valve assembly as claimed in claim 1, wherein saidresiliently connecting member is a closedly wound coil spring.

3. Levelling valve assembly as claimed in claim 1, wherein saidresilient connecting member is ositioned normally with a certainpredetermined idle gap reiative to said connecting lever.

4. Levelling valve assembly as claimed in claim 1, wherein saidsupporting shaft for said control lever is exposed at its both ends toopen atmosphere.

5. Levelling valve assembly as claimed in claim 1, wherein an air filtermade of a sintered porous metal is inserted between an inlet forintroducing the high pressure air and the air introducing valve providedand mounted in said main body.

1. A levelling valve assembly comprising: a. a main body positioned between a vehicle chassis and a vehicle axle and connected pneumatically with a high pressure air reservoir, a low pressure reservoir and a pneumatic spring; b. a drive shaft mounted in part of bore means formed in said main body, a chassis height sensing arm being supported on one end of said shaft and adapted for conversion of chassis height variation into a corresponding angular movement; c. a supporting shaft for supporting a valve-operating lever, said shaft being mounted in said housing with one end thereof extending into said bore means; d. a control lever fixedly attached to said supporting shaft; e. control valve means comprising a discharge valve and a supply valve, said valves being adapted for being controlled by said control lever; f. a damping mechanism provided between said drive shaft and said supporting shaft; g. a piston slidably mounted within said damping mechanism; h. a resilient connecting member, one end of the latter being kept in engagement with said drive shaft and the opposite end being kept in engagement with said piston; and i. a connecting lever one end of which is attached to said supporting shaft and the opposite end of which is adapted for cooperation with said resilient connecting member.
 2. Levelling valve assembly as claimed in claim 1, wherein said resiliently connecting member is a closedly wound coil spring.
 3. Levelling valve assembly as claimed in claim 1, wherein said resilient connecting member is positioned normally with a certain predetermined idle gap relative to said connecting lever.
 4. Levelling valve assembly as claimed in claim 1, wherein said supporting shaft for said control lever is exposed at its both ends to open atmosphere.
 5. Levelling valve assembly as claimed in claim 1, wherein an air filter made of a sintered porous metal is inserted between an inlet for introducing the high pressure air and the air introducing valve provided and mounted in said main body. 